High-pressure fuel reservoir

ABSTRACT

The invention relates to a high-pressure fuel reservoir a common rail fuel injection system of an internal combustion engine, with a plurality of fittings for connection fuel lines. In order to improve the mobility of the fuel lines in the connections, an intermediary piece is disposed in each of the fittings between the high-pressure fuel reservoir and the fuel lines.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 35 USC 371 application of PCT/DE 00/02528 filed onAug. 1, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a high-pressure fuel reservoir for a commonrail fuel injection system of an internal combustion engine, with anumber of fittings for fuel lines.

2. Description of the Prior Art

In common rail injection systems, a high-pressure fuel pump, possiblywith the aid of a presupply pump, supplies the fuel to be injected froma tank to the central high-pressure fuel reservoir, which is referred toas the common rail. Fuel lines lead from the rail to the individualinjectors which are associated with the cylinders of the internalcombustion engine. The injectors are individually triggered by theengine electronics as a function of the operating parameters of theengine in order to inject fuel into the combustion chamber of theengine. The pressure production and the injection are decoupled fromeach other by the high-pressure fuel reservoir.

A conventional high-pressure fuel reservoir is described, for example,in DE 195 48 611. The known high-pressure fuel reservoir is comprised ofan elongated, tubular body with a number of connections for supplyinginjectors. The ends of the fuel lines can only move to a limited degreein the fittings of the high-pressure fuel reservoir. The lack ofmobility of the fuel lines in the fittings of the high-pressure fuelreservoir turns out to be disadvantageous during installation of thehigh-pressure fuel reservoir in the engine.

The object of the invention is to embody a high-pressure fuel reservoirof the type described at the beginning so that the ends of the fuellines are sufficiently mobile in the fittings. Despite the sufficientmobility, the seal at these fittings should also be assured at highpressures. In addition, the high-pressure fuel reservoir according tothe invention should be simple in design and inexpensive to produce.

SUMMARY OF THE INVENTION

In a high-pressure fuel reservoir for a common rail fuel injectionsystem of an internal combustion engine with a number of fittings forfuel lines, the object is attained by virtue of the fact that anintermediary piece is disposed in each of the fittings between thehigh-pressure fuel reservoir and the fuel lines. The mobility of thefuel lines in the fittings is improved considerably by means of theintermediary piece. Manufacturing-and assembly-related tolerances can becompensated for by the improved mobility.

One particular embodiment of the invention is characterized in that theintermediary piece is essentially the shape of a hollow cylinder withtwo conical end faces which cooperate with complementary end faces inthe fuel line and in the high-pressure fuel reservoir. The conical endfaces produce a favorable sealing action when the complementary endfaces are braced against each other.

Another particular embodiment of the invention is characterized in thatan external thread is provided on the fitting, which cooperates with theinternal thread of a securing nut so that the fuel line is braced withits free end against the intermediary piece and the intermediary pieceis braced against the high-pressure fuel reservoir. The securing nutpermits the fuel lines to be rapidly mounted onto the high-pressure fuelreservoir.

Another particular embodiment of the invention is characterized in thatthe end of the intermediary piece oriented toward the high-pressure fuelreservoir and the end of the intermediary piece oriented away from thehigh-pressure fuel reservoir are tapered and that a radial supportsurface for the fuel line is embodied on the securing nut. Thesymmetrical embodiment of the intermediary piece simplifies itsinstallation because the installer does not have to pay attention to theorientation of the intermediary piece as it is inserted into thefitting.

Another particular embodiment of the invention is characterized in thatthe end of the intermediary piece oriented toward the high-pressure fuelreservoir is tapered, that the end of the intermediary piece orientedaway from the high-pressure fuel reservoir is funnel-shaped, and thatthe intermediary piece is supported with at least a part of its externalcircumferential surface against the internal circumferential surface ofthe fitting. If the intermediary piece has an asymmetrical shape, thenon the end face oriented toward the fuel line, it could be stretchedopen by the complementary end face of the fuel line. Such a stretchingopen is prevented by the fact that the intermediary piece is supportedwith at least a part of its outer circumferential surface against theinner circumferential surface of the fitting.

Another particular embodiment of the invention is characterized in thatthe fittings are welded onto the high-pressure fuel reservoir. Thisembodiment offers the advantage that the seal in relation to the outsideis produced directly at the high-pressure fuel reservoir. Theintersecting point between the fitting and high-pressure fuel reservoirdoes not have to be designed as high-pressure-tight. This reducesmanufacturing costs.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages, features, and details of the invention ensue from thefollowing description in which two exemplary embodiments of theinvention are described in detail with reference to the drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The accompanying FIGURE shows a detail from a longitudinal sectionthrough a high-pressure fuel reservoir according to the invention. Thehigh-pressure fuel reservoir shown is comprised of a tubular base body 1with an elongated, circular, cylindrical inner chamber 6. The innerchamber 6 of the tubular base body 1 communicates with an injector (notshown) of an internal combustion engine by means of a lateral connection7, a fitting 2, and a high-pressure fuel line 10.

For the sake of clarity, only one connection point is shown in theFIGURE represented. Naturally, a connection point for each injector isprovided on the tubular base body 1. Furthermore, the tubular base body1 is provided with additional connection points for the fuel supply,pressure sensors, etc.

The fitting 2 has the form of a stepped, circular, hollow cylinder withthree sections which have different diameters. The external thread isembodied on the section with the smallest diameter. The end face of thesection with the largest diameter is secured to the tubular base body 1by means of a welded connection 3.

Inside the fitting 2, the tubular base body 1 is provided with aconcentric raised area 4 in the form of a round disk. In the center ofthe raised area 4, there is a funnel-shaped opening 5, which feeds intothe lateral connection 7.

A tapering end 8 of an intermediary piece 9 rests against thefunnel-shaped opening 5 of the tubular base body 1 in a pressure-tightmanner. The intermediary piece 9 has the form of a hollow cylinder andis braced between the fuel line 10 and the tubular base body 1 with theaid of a securing nut 11. To this end, the internal thread of thesecuring nut 11 cooperates with the external thread of the fitting 2.After assembly, the fuel line 10 extends through a circular recess 18which is provided in the center of the securing nut 11.

The fitting 2, the intermediary piece 9, the fuel line 10, and thesecuring nut 11 are rotationally symmetrical parts. Two differentembodiments of the invention are shown to the left and right of therotational axis 19.

In the embodiment shown on the left side of the rotational axis 19, theintermediary piece 9 is tapered at its end 12 oriented away from thetubular base body 1. The tapered end 12 of the intermediary piece 9cooperates with a complementary sealing cone 13 on the fuel line 10. Inorder to prevent the end of the fuel line 10 resting against theintermediary piece from being stretched open, a support surface 14 isembodied on the securing nut 11 and rests against a collar 17 that isembodied at the end of the fuel line 10.

In addition, an annular clamping surface 15 is embodied on the end faceof the securing nut 11. The clamping surface 15 is used to press thesealing cone 13 embodied on the fuel line 10 against the tapered end 12of the intermediary piece 9. In addition, the tapered end 8 of theintermediary piece 9 is pressed into the funnel-shaped opening 5 of thetubular base body 1. A line 16 indicates that the fuel line 10 can bedeflected by an angle of approximately 10° after assembly.

An essential aspect of the current invention is that the interior of thefuel line 10 is connected by means of the intermediary piece 9 to theinner chamber 6 of the tubular base body 1 in a high-pressure-tightmanner without the connection between the fitting 2 and the tubular basebody 1 having to be designed as high-pressure-tight. There isnevertheless a sufficient mobility of the fuel line 10 afterinstallation, as indicated by the line 16.

In the embodiment shown on the right side of the rotational axis 19, theend 22 of the intermediary piece 9 oriented away from the tubular basebody 1 is embodied as funnel-shaped. The funnel-shaped end 22 of theintermediary piece 9 rests against a complementary sealing cone 23 whichis embodied at the end of the fuel line 10. In order to prevent theintermediary piece 9 from being stretched open in this region, a supportsurface 24 is provided on the fitting 2 and rests against the outercircumference of the intermediary piece 9.

The intermediary piece 9 is braced between the fuel line 10 and thetubular base body 1 by means of a clamping surface 25 that is embodiedon the securing nut 11. A line 26 indicates that sufficient deflectionof the fuel line 10 after assembly is possible in this embodiment aswell.

The mobility of the fuel line 10 is assured by the slight distancebetween the sealing cone 13, 23 at the end of the fuel line 10 and theclamping surface 15, 25. The recess 18 must also be of sufficient size.

The foregoing relates to preferred exemplary embodiments of theinvention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of the invention, thelatter being defined by the appended claims.

What is claimed is:
 1. In a high-pressure fuel reservoir for a commonrail fuel injection system of an internal combustion engine, with anumber of fittings (2) for fuel lines (10), the improvement comprisingan intermediary piece (9) is disposed in each of the fittings (2)between the high-pressure fuel reservoir (1) and the fuel lines (10),wherein the end (22) of the intermediary piece (9) oriented away fromthe high-pressure fuel reservoir (1) is funnel-shaped and that theintermediary piece (9) is supported with at least a part (24) of itsexternal circumference surface against the internal circumferencesurface of the fitting (2).
 2. The high-pressure fuel reservoiraccording to claim 1, wherein the intermediary piece (9) is essentiallythe shape of a hollow cylinder with two conical end faces (8; 12, 22)which cooperate with complementary end faces (5; 13, 22) on thehigh-pressure fuel reservoir (1) and the associated fuel line (10). 3.The high-pressure fuel reservoir according to claim 1, wherein thefittings (2) are welded onto the high-pressure fuel reservoir (1).
 4. Ina high-pressure fuel reservoir for a common rail fuel injection systemof an internal combustion engine, with a number of fittings (2) for fuellines (10), the improvement comprising an intermediary piece (9) isdisposed in each of the fittings (2) between the high-pressure fuelreservoir (1) and the fuel lines (10), wherein the intermediary piece(9) is essentially the shape of a hollow cylinder with two conical endfaces (8; 12, 22) which cooperate with complementary end faces (5; 13,22) on the high-pressure fuel reservoir (1) and the associated fuel line(10), and wherein an external thread is provided on the fitting (2),which cooperates with the internal thread of a securing nut (11) so thatthe fuel line (10) is braced with its free end against the intermediarypiece (9) and the intermediary piece (9) is braced against thehigh-pressure fuel reservoir (1).
 5. The high-pressure fuel reservoiraccording to claims 4, wherein the end (8) of the intermediary piece (9)oriented toward the high-pressure fuel reservoir (1) is tapered.
 6. Thehigh-pressure fuel reservoir according to claim 5, wherein the end (12)of the intermediary piece (9) oriented away from the high-pressure fuelreservoir (1) is tapered and that a radial support surface (14) for thefuel line (10) is embodied on the securing nut (11).
 7. Thehigh-pressure fuel reservoir according to claim 6, wherein the fittings(2) are welded onto the high-pressure fuel reservoir (1).
 8. Thehigh-pressure fuel reservoir according to claim 5, wherein the end (22)of the intermediary piece (9) oriented away from the high-pressure fuelreservoir (1) is funnel-shaped and that the intermediary piece (9) issupported with at least a part (24) of its external circumferencesurface against the internal circumference surface of the fitting (2).9. The high-pressure fuel reservoir according to claim 5, wherein thefittings (2) are welded onto the high-pressure fuel reservoir (1). 10.The high-pressure fuel reservoir according to claim 4, wherein thefittings (2) are welded onto the high-pressure fuel reservoir (1). 11.The high-pressure fuel reservoir according to claims 4, wherein the end(8) of the intermediary piece (9) oriented toward the high-pressure fuelreservoir (1) is tapered, wherein the fittings (2) are welded onto thehigh-pressure fuel reservoir (1).
 12. The high-pressure fuel reservoiraccording to claim 11, wherein the end (12) of the intermediary piece(9) oriented away from the high-pressure fuel reservoir (1) is taperedand that a radial support surface (14) for the fuel line (10) isembodied on the securing nut (11).
 13. The high-pressure fuel reservoiraccording to claim 4, wherein the end (8) of the intermediary piece (9)oriented toward the high-pressure fuel reservoir (1) is tapered.
 14. Thehigh-pressure fuel reservoir according to claim 13, wherein the end (12)of the intermediary piece (9) oriented away from the high-pressure fuelreservoir (1) is tapered and that a radial support surface (14) for thefuel line (10) is embodied on the securing nut (11).
 15. Thehigh-pressure fuel reservoir according to claim 13, wherein the fittings(2) are welded onto the high-pressure fuel reservoir (1).
 16. Thehigh-pressure fuel reservoir according to claim 4, wherein the end (22)of the intermediary piece (9) oriented away from the high-pressure fuelreservoir (1) is funnel-shaped and that the intermediary piece (9) issupported with at least a part (24) of its external circumferencesurface against the internal circumference surface of the fitting (2).17. The high-pressure fuel reservoir according to claim 4, wherein theend (22) of the intermediary piece (9) oriented away from thehigh-pressure fuel reservoir (1) is funnel-shaped and that theintermediary piece (9) is supported with at least a part (24) of itsexternal circumference surface against the internal circumferencesurface of the fitting (2).
 18. The high-pressure fuel reservoiraccording to claim 4, wherein the fittings (2) are welded onto thehigh-pressure fuel reservoir (1).
 19. In a high-pressure fuel reservoirfor a common rail fuel injection system of an internal combustionengine, with a number of fittings (2) for fuel lines (10), theimprovement comprising an intermediary piece (9) is disposed in each ofthe fittings (2) between the high-pressure fuel reservoir (1) and thefuel lines (10), the intermediary piece (9) being essentially the shapeof a hollow cylinder with two conical end faces (8; 12) which cooperatewith complementary end faces (5; 13) on the high-pressure fuel reservoir(1) and the associated fuel line (10), the two conical end faces areboth convex faces.